Isolated nucleic acid molecule which codes for a 32 kDa protein having 11-cis retinol dehydrogenase activity, and which associates with P63, a portion of a retinol binding protein receptor

ABSTRACT

In accordance with this invention, an RPE cell membrane associated protein which has a molecular weight of about 32 kd, as determined by SDS-PAGE, has been discovered. This protein, referred to an &#34;p32,&#34; forms an oligomeric protein complex with the previously characterized p63 protein, a component of the membrane receptor for RBP. A nucleic acid molecule which codes for the p32 protein has also been isolated and sequence analysis shows that the p32 protein belongs to the family of short chain alcohol dehydrogenases, and exhibits 11-cis retinol dehydrogenase activity, the enzyme which catalyzes conversion of 11-cis-retinol into 11-cis retinaldehyde.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/375,962, filed Jan. 20, 1995, now U.S. Pat. No. 5,731,195, which is itself a continuation in part of application, Ser. No. 08/258,418 filed Jun. 10, 1994, now abandoned. Both applications are incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a protein having 11-cis retinol dehydrogenase activity, and which forms a complex with a specific portion of a membrane receptor for plasma retinol-binding protein (RBP) expressed, e.g., in retinal pigment epithelium (RPE), and more specifically a 32 kDa protein having 11-cis retinol dehydrogenase activity, which forms a complex with a 63 kDa RBP-binding membrane protein. The invention also involves isolation of the 32 kDa protein (p32), as well as nucleic acid molecules coding for p32 or complimentary to coding sequences therefor, in addition to various applications of these materials.

BACKGROUND AND PRIOR ART

Retinoids (vitamin A-derivatives) have important physiological functions in a variety of biological processes. During embryonic growth and development, as well as during growth and differentiation of adult organisms, retinoids act as hormones and participate in the regulation of gene expression in a number of cell types. See Lied et al. Trends Genet., 17:427-433 (1992). It is believed that the effects of these molecules are mediated through two classes of nuclear ligand-controlled transcription factors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs), Benbrook et al., Nature, 333:669-672 (1988); Brand et al., Nature, 332:850-853 (1988); Giguere et al., Nature, 330:624-629 (1987); Mangelsdorf et al., Nature, 345:224-229 (1990); Mangelsdorf, et al. Genes Dev. 6:329-344 (1992); Petkovich et al. Nature 330:440-450 (1987); and Zelent et al., Nature 339:714-717 (1989).

Apart from their role as hormones in cellular growth and differentiation, retinoids are also involved in the visual process as the stereo isomer 11-cis retinaldehyde of retinaldehyde is the chromophore of the visual pigments. See, e.g. Bridges, The Retinoids, Vol. 2, pp 125-176, Academic Press, Orlando, Fla., (1984).

Under normal physiological conditions most cells, both ocular and non-ocular, obtain all-trans retinol as their major source of retinoids. Despite the many different metabolic events taking place in different tissues, it is known that a common extracellular transport machinery for retinol has evolved. Specifically, in plasma, retinol is transported by plasma retinol binding protein (RBP). See Goodman et al., The Retinoids, Academic Press, Orlando Fla., Volume 2, pp. 41-88 (1984). The active derivatives of retinol, i.e., retinoic acid in non-ocular tissues and mostly 11-cis retinaldehyde for ocular tissues, are generated by cellular conversion of trans-retinol, using specific mechanisms. To date, none of these mechanisms have been fully defined at the molecular level and several of the enzymes involved have only been identified by enzymatic activities. See Lion et al., Biochem. Biophys. Acta. 384:283-292 (1975); Zimmermann et al., Exp. Eye Res. 21:325-332 (1975); Zimmermann, Exp. Eye Res. 23:159-164 (1976) and Posch et al., Biochemistry 30:6224-6230 (1991).

Polarized retinal pigment epithelial cells (polarized RPE) are unique with regard to retinoid uptake since all-trans retinol enters these cells via two different mechanisms. Retinol accumulated from RBP is taken up through the basolateral plasma membrane, while all-trans retinol, presumably taken up from the interstitial retinol-binding protein (IRBP) following bleaching of the visual pigments, may enter through the apical plasma membrane. See Bok et al., Exp. Eye Res. 22:395-402 (1976); Alder et al., Biochem. Biophys. Res. Commun. 108:1601-1608 (1982); Lai et al., Nature 298:848-849 (1982); and Inu et al., Vision Res. 22:1457-1468 (1982).

The transfer of retinol from REP to cells is not fully understood. In a number of cell types, including RPE, specific membrane receptors for RBP have been identified. This is consistent with a receptor-mediated uptake mechanism for retinol. For example isolated retinal binding protein receptors, nucleic acid molecules coding for these receptors and antibodies binding to the receptor have been taught, in references relating to the first of the two mechanisms. See Bavik et al., J. Biol. Chem. 266:14978-14985 (1991); Bavik, et al. J. Biol. Chem. 267:23035-23042 1992; Bavik et al., J. Biol. Chem. 267:20540-20546 (1993); and copending U.S. application Ser. No. 083,539 and International Publication WO 93/23538, all of which are incorporated by reference herein. See also Heller, J. Biol. Chem. 250:3613-3619 (1975); and Bok et al., Exp. Eye Res. 22:395-402 (1976).

Retinol uptake on the apical side of the RPE for the regeneration of 11-cis retinaldehyde, is less well characterized. Regardless of the origin of all-trans retinal, however, the synthesis and apical secretion of 11-cis retinaldehyde seems to be the major pathway for accumulated retinal in the RPE. At present, it is not known whether similar mechanisms are used with regard to cellular retinal uptake through the basolateral and the apical plasma membranes. Available data do show that functional receptors for RBP are exclusively expressed on the basolateral plasma membrane of RPE-cells. Bok et al., Exp. Eye Res. 22:395-402 (1976).

It is also known that RPEs express a 63 kDa protein (p63). This molecular weight, and all others, is by reference to SDS-PAGE, unless stated otherwise. It has also been shown by chemical cross-linking that this protein may be part of an oligomeric protein complex which functions as a membrane receptor for plasma retinol-binding protein (RBP) in RPEs, or a component of the retinoid uptake machinery in RPE cells. See Bavik et al, J. Biol. Chem. 266:14978-14875 (1991); Bavik et al., J. Biol, Chem. 267:23035-23042 (1992), U.S. patent application Ser. No. 083,539 and PCT application WO93/23538. The p63 protein has been isolated and the corresponding cDNA cloned. See Bavik et al., J. Biol. Chem. 267:20540-20546 (1993). Nothing in these references suggests the existence of the protein which is a feature of this invention.

SUMMARY OF THE INVENTION

In accordance with this invention, RPE membrane associated proteins which have a molecular weight of about 32 kd, as determined by SDS-PAGE, are disclosed. These proteins, referred to as "p32," form oligomeric protein complexes with the previously characterized p63 protein, a component of the membrane receptor for RBP. Also disclosed are nucleic acid molecules which code for the p32 protein. Sequence analysis shows that the p32 protein belongs to the family of short chain alcohol dehydrogenases, and exhibits 11-cis retinol dehydrogenase activity, the enzyme which catalyzes the stereospecific conversion of 11-cis retinol into 11-cis retinaldehyde in the presence of cofactor NAD+.

As will be shown, p32 has many important uses. For example, owing to its membrane bound 11-cis-retinol dehydrogenase activity, which catalyzes the conversion of 11-cis-retinol to 11-cis-retinaldehyde, a major metabolic step in retinoid metabolism in RPE-cells, retinoid accumulation and metabolism which may lead to retinitis pigmentosa, may be directly or indirectly tied to the presence of p32, and/or its activation or inhibition. As p32 has also been found to be a member of the short chain alcohol dehydrogenase super family, many known alcohol dehydrogenase inhibitors (and activators) are available to develop activity assays, and thus diagnostic materials for retinol uptake, and ocular retinoid metabolism.

Particular features of the invention include nucleic acid molecules which encode mammalian forms of these proteins, such as human, bovine, and murine forms. Also a part of the invention are probes, based upon extended sequences as described herein.

These and other aspects of this invention are more fully discussed in the following specification with accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows SDS-PAGE analysis of radiolabeled protein from RPE-membranes and immunoprecipatation with mAb A52 against p63.

FIG. 1B shows SDS-PAGE analysis of RPE-membrane proteins bound and eluted through an mAb A52 immunoaffinity column, and the presence of p32 in the eluted fraction from the immunoaffinity column.

FIG. 2A shows visualization via agarose gel electrophoresis of a 61 bp PCR-amplified fragment using oligonucleotide mixtures OM1 and OM3, both derived from peptide 321 deduced from partial amino acid sequence determination of trypsin digested p32.

FIG. 2B shows visualization of a 330 bp PCR-amplified fragment using oligonucleotide mixtures OM2 and OM3, derived from peptides p323 and p321, respectively, as deduced from partial amino acid sequence determination of trypsin digested p32.

FIG. 3 illustrates the nucleotide sequence of pλ321 and the deduced amino acid sequence of p32, with the partial amino acid sequences determined from peptides isolated from trypsin digested p32. Refer to SEQ. ID. NO:10

FIG. 4 illustrates amino acid sequence alignments of p32 and some related proteins belonging to the family of short-chain alcohol dehydrogenases. The sequence of these proteins are set forth in SEQ. ID. NO: 11 (rat D-b hydroxybutyrate dehydrogenase (rDBH)), SEQ. ID. NO: 12 (human estradiol 17-b dehydrogenase (hEDH)), SEQ. ID. NO: 13 (E. Coli 3-exoacyl [acyl carrier protein] reductase (FABg)), and SEQ. ID. No; 14 (p32).

FIG. 5 illustrates analysis of the amino acid sequence of p32.

FIG. 6 illustrates membrane interaction of p32 synthesized in vitro.

FIG. 7 illustrates the restricted expression of transcripts corresponding to p32.

FIG. 8A illustrates expression of p32 in transfected cells for further enzymatic activity analysis of 11-cis retinol dehydrogenase activity.

FIG. 8B illustrates the expression of 11-cis retinol dehydrogenase activity in the presence of NAD+ as indicated by the formation of 11-cis retinaldehyde.

FIG. 8C illustrates the lack of 11-cis-retinol dehydrogenase activity in the presence of cofactor NADP.

FIG. 8D illustrates control cells not expressing p32 which lack the ability to oxidize 11-cis-retinol into 11-cis-retinaldehyde.

FIG. 9 shows the structure of the human 11-cis-retinol dehydrogenase gene.

DETAILED DISCUSSION OF PREFERRED EMBODIMENTS

It is known that plasma retinol binding protein (RBP) can be chemically cross-linked to a high molecular weight complex of a 63 kDa protein (p63) receptor of retinal pigment epithelium membranes (RPE), forming an RBP-RBP receptor complex with elution properties of globular proteins of similar sizes having apparent molecular weights of approximately M_(r) 150,000 and 450,000. See Bavik et al, J. Biol. Chem. 266:14978-14875 (1991), and Bavik et al., J. Biol. Chem. 267:23035-23042 (1992). The protein responsible for binding of RBP, expression of which is restricted to RPE, has been identified as a 63 kDa protein (p63). Through the generation of a monoclonal antibody A52 (mAb A52) to the 63 kDa protein which binds the RBP-RBP receptor complex and p63, and immunoaffinity chromatographic analysis, it has been found that the majority of p63 elutes as a monomer, with a significant portion of the protein found in positions corresponding to higher molecular weight species. This indicates that p63 exists in an oligomeric protein complex with other protein components. Bavik et al., J. Biol. Chem. 266:14978-14985 (1991), and Bavik et al, J. Biol. Chem. 267:23035-23042 (1992). Therefore, the following procedure was carried out to investigate the molecular characteristics of such oligomeric protein complexes, and whether p63 forms a complex with other proteins specific to RPE. The results show that a 32 kDa membrane associated protein (p32) indeed forms a complex with p63.

EXAMPLE 1

Bovine RPE-cells were isolated and membrane fractions were prepared as described in Bavik et al, J. Biol. Chem. 266:14978-14875 (1991) incorporated by reference. RPE-membrane proteins were then solubilized in phosphate-buffered saline (PBS)(20 mM sodium phosphate, pH 7.2, containing 150 mM NaCl), containing 1% 3-[(3-cholamido-propyl)-dimethylammonio]-1-propane sulfonic acid (CHAPS) at 1 mg of total membrane protein/ml of buffer. Remaining material was removed by ultracentrifugation at 100,000×g for 1 hour. Next, 500 ul aliquots of the solubilized membranes were subjected to gel filtration on a Sepharose 6 column equilibrated in PBS containing 1% CHAPS. The column was operated at a flow rate of 0.2 ml/min and 500 ul fractions collected. Proteins eluted in fractions corresponding to globular proteins of M_(r) 150,000 to 400,000 were then radiolabelled with Na¹²⁵ I using the well-known Chloramin T procedure. Non-incorporated,¹²⁵ I was removed by gel filtration on Sepahadex G-25 packed in a Pasteur pipette.

Aliquots of the radiolabelled proteins were then diluted in PBS containing 1% CHAPS and 1% bovine serum albumin and subsequently subjected to immunoprecipitation using mAb A52, which specifically binds to p63 (5 ug per incubation) or by using two polyclonal rabbit antisera to p63 (3 ul of serum per incubation) See Bavik et al., J. Biol. Chem. 267:23035-23042 (1992). Non-specific immunoprecipitation was monitored in parallel incubations using an unrelated mAb and preimmune rabbit serum. Fifty ul of a 50% slurry of protein A-Sepharose was added to the incubations for 30 minutes. The beads were subsequently carefully washed with PBS containing 1% CHAPS and the eluted material then prepared for SDS-PAGE analysis, was carried out according to the classic method of Blobel et al. J. Cell. Biol. 67:835-851 (1975).

Referring now to FIG. 1A, autoradiograms of the SDS-PAGE gels showed that both types of reagents reacted with p63, whereas the unrelated mAb or preimmune rabbit serum did not precipitate p63. In all lanes containing immunoprecipitated p63 there was an enrichment of a M_(r) 32,000 protein. Since both mAb A52 and the rabbit antisera to p63 are highly specific for p63 (See, for example, Bavik et al., J. Biol. Chem. 267:23035-23042 (1992)), it can be concluded that the M_(r) 32,000 protein (p32) coprecipitated in the aforesaid analysis by binding to p63. The analysis also identified a double band of M_(r) 50,000-52,000 which precipitated along with p32 and p63 (FIG. 1D, E).

EXAMPLE 2

Experiments were then carried out to identify p32. Advantage was taken of the fact that p32 specifically interacts with p63 as shown supra. Thus, detergent solubilized RPE-membrane proteins were passed over an immunoaffinity column containing mAb A52. Referring now to FIG. 1B, lane b, following a washing procedure, bound proteins were eluted at high pH in a CHAPS-containing buffer, and SDS-PAGE analysis and Coomassie staining of the eluted fractions revealed p63 to be specifically retained and eluted from the immunoaffinity column. Further, a weekly stained band corresponding to p32 could be visualized in the eluate from the A52 column. As shown in FIG. 1B, a comparison of the total protein profile of solubilized RPE membranes and the eluted fraction from the A52 column show that the p32 protein is not efficiently retained therein. However, the appearance of p32 in the eluted fraction from the A52 column, but not in the eluted fraction from the column containing an unrelated Ig, indicate a specific interaction of p32 with p63. This result is consistent with previous immunoprecipitation data, and shows that p32 is complexed to p63 and is retained on the immunoaffinity column due to, this complex formation.

Following identification of p32 as a component of a complex with p63 in RPE-membranes, the p32 protein itself was isolated by SDS-PAGE of eluted fractions of solubilized RPE-membranes from the A52 immunoaffinity column, as set forth below in Example 3.

EXAMPLE 3

RPE-membranes were solubilized in PBS containing 1% CHAPS as set out above and then incubated with mAb A52 Ig coupled to CNBr-activated Sepharose 4B beads (Pharmacia) in a Bio-Rad poly prep column (Bio-Rad) by end-over-end rotation at +4° C. Following a 2 hour incubation, the beads were allowed to settle and the column was quickly washed with 5 column volumes of PBS containing 1% CHAPS. Bound proteins were then eluted with 50 mM triethanolamine buffer (pH 11.2) containing 1% CHAPS. The pH of the eluate was quickly adjusted to 8.0 by the addition of 1M Tris-HCl buffer containing 1% CHAPS. The eluted fractions were subjected to SDS-PAGE, and the separated proteins then visualized by Coomassie Blue staining. A band corresponding to p32 (SDS-PAGE, 32 kDa), was found.

To determine the primary structure of p32, partial amino acid sequence analysis of the isolated protein was undertaken by first cutting out a portion of the aforesaid Coomassie stained band corresponding to approximately 2-5 ug of the 32kDa protein, then lyophilizing the gel piece to dryness. The gel was rehydrated in buffer containing modified trypsin and incubated to generate various peptides for extraction and analysis. A preferred procedure is set forth below in Example 4.

EXAMPLE 4

Coomassie stained bands containing the p32 protein from Example 3 were excised and treated according to Rosenfeld et al. Anal. Biochem. 15:173-179 (1992) with minor modifications. The gel pieces were washed twice for 30 min at 30° C. with 100 ul of 0.2M ammonium bicarbonate buffer containing 50% acetonitrile and thereafter completely dried under a stream of nitrogen. The gel pieces were subsequently rehydrated with 5 ul of 0.2M ammonium bicarbonate buffer containing 0.02% Tween 20 and 0.5 ug of modified trypsin. Trypsin was added from a stock solution prepared in 1 mM HCl. Rehydration was continued by the addition of 5 ul portions of the 0.2M ammonium bicarbonate buffer until the gel pieces rehydrated to their original sizes. The rehydrated gel pieces were then incubated overnight at 30° C. Protease activity was inhibited by the addition of trifluoroacetic acid (TFA) to a final concentration of 1%. The supernatant was recovered and combined with two extracts made with 150 ul of 0.1% TFA in 60% acetonitrile. The organic phase was reduced and the digest was subjected to HPLC using a reverse phase mRPC C2/C18 SC 2.1/10 column operated in a SMART system. The sample was eluted with a gradient of acetonitrile in 0.065% TFA and fractions containing discrete peptides were collected using the automatic peak fractionation option. Five of the identified peptides were selected for amino acid sequence analysis using an ABI 470A sequencer equipped with a model 120A PTH analyzer (applied Biosystems Inc. Foster City, Calif.). The results are set forth below in Table 1.

                                      TABLE 1                                      __________________________________________________________________________     Amino acid sequences determinations of                                         five peptides isolated from trypsin digested p32.                              __________________________________________________________________________     p321 L-V-E-A-V-L-A-E-V-L-P-K-P-A-Q-T-V-A                                                                    (SEQ ID NO: 1)                                            (D).sup.a       (W)                 (Y)                                P322 Y-S-P-G-W-D-A-K         (SEQ ID NO: 2)                                    P323 T-P-V-T-N-L-E-T-L-E-D-T-L-Q-A                                                                          (SEQ ID NO: 3)                                    P324 D-V-A-P-F-G-V           (SEQ ID NO: 4)                                    P325 L-H-T-T-L-L-D-V-T-D-P-Q-S-I                                                                            (SEQ ID NO: 5)                                    __________________________________________________________________________      .sup.a The amino acid residues given within the parentheses are the            residues deduced from the cDNA sequence in the same positions.           

Protein SEQ ID NOS: 1-5 can be used alone or ligated to hapten by well known methods.

Next, to determine the complete primary structure of p32, four degenerative oligonucleotide mixtures, OM1-OM4, as set forth below in Table 2 were synthesized based on the amino acid sequences of the p321 and p323 sequenced peptides of Table 1. The procedure is as follows in Example 5.

EXAMPLE 5

Four degenerate oligonucleotide mixtures derived from peptides p321 and p323 were synthesized using well-known techniques. The two sense mixtures (OM1 and OM3) were derived from the N-terminal amino acids 1-5 of p321 and 2-6 of p323. The antisense mixtures (OM2 and OM4) were derived from amino acids 12-17 of p321 and 10-15 of p323. All nucleotide mixtures were synthesized with a 4 bp 5' extension and an Eco RI-site for subsequent cloning of the PCR products. The sequences of the oligonucleotide mixtures are set out below in Table 2, and the Eco RI-site is underlined. Positions containing all four bases are marked N.

                  TABLE 2                                                          ______________________________________                                         OM1:ACGT GAA TTC TN GTN GARGCN GT (SEQ ID NO: 6)                               OM2:ACGT GAA TTC AC NGTYTG NGC NGGYTT (SEQ ID NO: 7)                           OM3:ACGT GAA TTC CCN GTN ACN AAYYT (SEQ ID NO: 8)                              OM4:ACGT GAA TTC GCYTG NARNGTRTCYTC (SEQ ID NO: 9)                             ______________________________________                                    

Single stranded "complementary" cDNA from reverse transcribed RPE mRNA and four combinations of the above-described degenerate nucleotide mixtures were employed in polymerase chain reactions (PCR) using a standard procedure. Following the amplification procedure, aliquots of the PCR reaction products were analyzed by agarose gel electrophoresis. The procedure is set out below in Example 6.

EXAMPLE 6

To carry out the PCR amplifications, first strand cDNA was synthesized by standard procedures using avian myelostosis virus reverse transcriptase. Twenty ug of total RNA from isolated RPE-cells were used and the reaction was primed with oligo (dT) 15. Aliquots corresponding to 2 ug of total RNA was used in each subsequent PCR reaction. The PCR reactions were performed using a final concentration of 0.5 uM of the oligonucleotide mixtures in a 100 ul reaction. Taq polymerase was used. Following 30 cycles (2 minute at 95° C., 1 minute at 55° C. and 2 minute at 72° C.), aliquots of the reactions were analyzed on 4% GTG agarose gel containing 5 ug/ml of ethidium bromide.

As shown in FIG. 2A, amplifications using the oligonucleotide mixtures OM1 and OM2, both derived from peptide p321, resulted in an amplified 61 bp fragment. Amplifications using mixtures OM3-OM4 and OM1-OM4 failed to yield any products. Finally, as shown in FIG. 2B, amplification using OM3-OM2 resulted in an amplified 330 bp fragment.

Subsequent sequence analysis of the 61 bp and 330 bp fragments confirmed that cDNA sequences have been amplified which corresponded to the peptide sequences generated in the previous amino acid sequence analysis. Differences between the deduced amino acid sequences from amplified PCR fragments and the generated amino acid sequence of peptide p321 indicates the generation of specific probes suitable for the isolation of full length cDNA clones encoding p32.

To isolate a full length cDNA clone, an RPE-specific lambda ZAP-II cDNA library was screened with the 330 bp fragment as the probe. Five independent lambda clones were isolated from approximately 200,000 clones, and subcloned by in vivo excision. The cDNA clone pλ321 contained the longest insert, (approximately 1.1 Kb), and was selected for use in further studies.

Both strands of pλ321 were fully sequenced with the insert being 1104 bp long, excluding linkers used to prepare the cDNA library. The procedure is set out below in Example 7.

EXAMPLE 7

The amplified products using OM1-OM2 (61 bp) and OM3-OM2 (330 bp) were digested with EcoRI, gel purified and cloned into EcoRl-cut vector pBS. The ³² P-labelled 330 bp fragment was used to screen a RPE-specific λZAP II cDNA library as previously described by Bavik et al., J. Biol. Chem. 267:20540-20546 (1993), incorporated by reference. Five positive λ clones were isolated and the inserts were subcloned in pBluescript by in vivo excision following the manufacturer's instructions. Clone pλ321 contained an insert of 1.1 Kb, and both strands were fully sequenced using Sequenase with T3, T7 or M13 universal primers or with internal primers.

The nucleotide sequence of pλ321 and the predicted amino acid sequence of p32 are shown in FIG. 3 and SEQ ID NO: 10. Nucleotides are numbered on the left and amino acid residues on the right. Amino acid 1 is initial methionine ("Met").

As shown in FIG. 3, the 1.1 kbp insert contains one long open reading frame encoding 318 amino acid residues with a calculated mass of 35,041D. The first methionine residue lies in a good context according to the Kozak rules for transcription initiation and is likely to be the initiation codon. See Kozak, Cell, 44:283-292 (1986). This inference is strengthened by the fact that in vitro translation of synthetic mRNA transcribed from pλ321 gives rise to a M_(r) 32,000 protein (SDS-PAGE analysis), as set out below, but there is no stop codon in frame in the upstream 35 bp 5'-untranslated region of the cDNA. As also shown in FIG. 3, the 100 bp 3'-untranslated region ends with a putative polyA-tract, and a polyA-signal was identified in the upstream sequence (bp 1104-1110).

The deduced amino acid of pλ321 and the amino acid sequences of the five generated tryptic peptides (Table 1) differ in only 3 positions out of the 62 residues available for a comparison. All 3 differences are found in the peptide p321 but the nucleotide sequence in this region of a second cDNA clone (pλ324) is identical to that of pλ321. This indicates that the amino acid sequence determination of peptide p321 was probably incorrect although it cannot be excluded that the differences are due to the presence of different alleles of p32. These data demonstrate that pλ321 contains the complete coding region of p32.

Again, referring to FIG. 3, a consensus sites for N-linked glycosylation (amino acid residues N-I-T) could be found in the deduced amino acid sequence at position 160-162.

Additionally, it has been found that p32 shows sequence similarities to short-chain alcohol dehydrogenases. Referring now to FIG. 4 a search through the Swissprot protein data base revealed that p32 is structurally related to several previously sequenced proteins. It is most closely related to a mitochondrial matrix dehydrogenase, the D-β-hydroxybutyrate dehydrogenase (BDH) Churchill et al; Biochem. 31:3793-3799 (1992) and shows less but significant similarities to two other proteins, the 3-oxoacy[acyl carrier protein] reductase from E. coli (Rawlings et al., J. Biol. Chem. 267-5751-5754 (1992)) and the human estradiol 17 β-dehydrogenase (Peltoketo et al., FEBS Lett., 239:73-77 (1988) and Leu et al., Mol. Endocrinol. 3:1301-1309 (1989)). All the related proteins fall into the protein super-family of short-alcohol dehydrogenases. This protein superfamily comprises approximately 50 different proteins (Persson et al, Eur. J. Biochem, 200:537-593 (1991)). The overall sequence homology between p32 and BDH is around 39w. The level of homology to the E. coli reductase and to the estradiol 17-β-dehydrogenase is lower (31% and 33%, respectively).

Optimal multiple alignment identified several conserved regions shared by p32 and the most closely related proteins (boxed areas in FIG. 4). The first region involving residues 63-69 (using the numbering in FIG. 4) which displayed the conserved motif G-X-X-X-G-X-G is believed to be the binding site for cofactors NAD, NADP or its reduced forms. Another conserved region is found between residues 148-153 (consensus sequence L-V-N-N-A-G) but no functional characteristics have yet been attributed to that sequence motif. The sequence motif Y-X-X-X-K, thought to be the active site, is the most highly conserved motif in short-chain alcohol dehydrogenases and is present in p32 residues 175-179 See Persson et al., Eur. J. Biochem, 200:537-593 (1991). These similarities demonstrate that p32 exhibits several features of a functional short-chain alcohol dehydrogenase.

As shown in FIG. 5, hydropathy analysis of the amino acid sequence of p32 reveals several hydrophobic stretches, indicating that p32 is a membrane-associated protein. The first 18 amino acids are hydrophobic, and this region has characteristics of a classical signal sequence. However, a consensus site for signal peptidase cleavage could not be identified. See Von Heijne, Nucl. Acid Res., 14:4683-4690 (1986). The amino acids between residues 130 to 150 are hydrophobic and there is a relatively long hydrophobic stretch near the C-terminus of the protein. Thus, p32 displays several hydrophobic regions which are potential membrane spanning segments. In light of the homology to the family of short-chain alcohol dehydrogenases as shown above, it is likely that the central hydrophobic region of p32 (residues 130-150) is not used as a membrane anchor. Instead, both the N-terminal and the C-terminal regions are potential membrane anchoring domains.

To determine the mode of interaction of p32 with membranes, p32 was synthesized by in vitro translation using a reticulocyte lysate system with mRNA transcribed from linearized pλ321. The procedure is set out in Example 8 infra.

EXAMPLE 8 Expression of p32 by in vitro translation

In vitro transcribed mRNA encoding p32 was synthesized from linearized Pλ321 using T7 RNA polymerase. In vitro translation reactions were carried out using nuclease treated rabbit reticulocyte lysate following the manufacturer's instructions. Fifty ng of mRNA was included in each reaction, with or without the addition of dog pancreatic microsomes. To isolate membrane inserted p32, the microsomes were collected by centrifugation at 12,000×g for 10 min at 4° C. The microsomes were carefully resuspended in PBS and recentrifugated.

As shown in FIG. 6, translation in the presence of dog pancreatic microsomes showed that p32 becomes almost quantitatively membrane associated and migrates as a M_(r) 32,000 species in SDS-PAGE. Translation in the absence of acceptor membranes similarly yields a M_(r) 32,000 protein. These data indicate that the N-terminal hydrophobic sequence acts as a signal sequence but it is not removed by the signal peptidase, and such supports the previous observation that a consensus site for signal peptidase cleavage could not be identified in the deduced primary sequence.

The tissue expression of p32 was analyzed by Northern blotting analyses using total RNA isolated from bovine RPE, liver, kidney, adrenal, lung, testis, brain and muscle. The procedure is set out in Example 9.

EXAMPLE 9 Northern blot analyses

Twenty ug of total RNA isolated from a number of tissues was electrophoresed on a 1% agarose under denaturing conditions and transferred to a Hybond-N nylon filter. The filter was hybridized with ³² P-labelled full length cDNA encoding p32 under stringent conditions. The details of the isolation of total RNA, hybridization conditions and washing procedure were identical to those previously described in Bavik, et al., J. Biol. Chem. 267:20540-20546 (1993).

Hybridization at high stringency with the 1.1 Kb insert of pλ321 as the probe, revealed abundant expression of transcripts corresponding to p32 only in RPE but not at a detectable level in several other tissues. The size of the major transcript was 1.4 kb but other less abundant transcripts could be visualized after prolonged exposure of the filters both in RPE as well as in other tissues.

EXAMPLE 10 Expression of p32 in COS-cells and enzymatic analysis of the properties of recombinant p32.

p32 was first expressed in COS-cells using a eukaryotic expression vector, and then microsome fractions from transfected cells and control cells were subjected to immunoblotting analysis to verify the expression of p32 at the desired levels, as follows:

Specifically, the EcoRI insert of p λ 321 was cloned into the EcoRI-digested eucaryotic expression vector pSG5. See Green et al., Nucl. Acid Res. 16:39 (1988). COS-cells were maintained in Dulbecco's minimal essential medium supplemented with 10% fetal bovine serum, 2 mM glutamine and antibiotics. The cells were seeded into 60 mm petri dishes (4×10⁵ cells per dish) and transfected with 5 ug of plasmid per dish using DEAE dextran. Control cells were transfected with equal amounts of the parental vector alone. After treatment with 10% DMSO for 2 minutes, the cells were incubated for 72-96 hours, and then harvested by scraping the dishes with a rubber policeman, and the cells thereafter collected by low speed centrifugation. The collected cell pellets were next resuspended in hypotonic buffer (10 mM Tris-HCl, pH 7.5, containing 1 mM phenyl-methylsufonyl fluoride), put on ice for 20 minutes, and then homogenized using a Dounce homogenator. Unbroken cells and debris were removed by centrifugation (3000×g)for 15 minutes. Microsomes were subsequently collected by ultra-centrifugation at 100,000×g for 1 hour; membrane pellets were stored at -80° C. until further analyzed.

Antisera to p32 were generated by injecting rabbits with p32 (amino acid residues 19-318) expressed as a fusion protein with GST. The bacterial expression vector pGEX 2T was used and the GST-fusion protein was induced and purified, as recommended by the supplier (Pharmacia). Each rabbit received a subcutaneous injection of 75 ug of fusion protein emulsified in Freunds complete adjuvant. The rabbits were boostered with 50 ug of fusion protein emulsified in Freunds incomplete adjuvant every rabbit sera were passed over a column containing GST fusion-protein immobilized on CNBr activated Sepharose beads. Bound Ig was eluted with 0.1M sodium citrate buffer (pH 3.0), containing 0.5M NaCl. To remove Ig to the GST portion of the fusion protein, the eluted Ig was similarly incubated with GST-coupled Sepharose beads and the unbound Ig fraction was used. For immunoblot analysis of the over expressed protein, the Ig was used at a concentration of 1 ug per ml. The details of the immunoblotting procedure are described in detail in Bavik et al., J. Biol. Chem., 267:23035-23042 (1992) the disclosure of which is herein incorporated by reference.

As shown in FIG. 8A, the above procedure resulted in expression of p32 in cells transfected with the recombinant expression vector, but not in control cells that were mock transfected.

Next, the enzymatic properties of p32 expressed in COS-cells was assayed in a manner similar to that as described in the study of 11-cis-retinol dehydrogenase activity in microsomal fractions of RPE cells. See Saari et al., Anal. Biochem 213:28-13226 (1993).

In particular, the enzymatic activity of p32 was confirmed by incubating the microsomal fractions from the aforementioned transfected cells, and from control cells lacking p32, with varying combinations of the different stereo isomeric substrates, i.e., 11-cis-retinol or all-trans-retinol, in the presence of either cofactor NAD+ or NADP.

To prepare the substrate, 11-cis retinol was synthesized from 11-cis-retinaldehyde using sodium borohydride, as set fourth in Heller et al., J. Biol. Chem. 248:6308-6316 (1973), and stored under argon at 80° C. HPLC analysis confirmed the quantitative reduction of 11-cis-retinaldehyde to 11-cis-retinol, and all manipulations with the retinoids were done under subdued lighting conditions.

To assay for p32 activity in transfected cells, the final concentration of 11-cis-retinol and all-trans-retinol (obtained from Sigma Chemical Co.) in the incubations was reduced to 100 uM. Twenty ug of total membrane protein from COS-cells expressing p32 or from control cells were used in each incubation, and thereafter a 30 minute incubation at 37° C. in the presence or absence of NAD+ or NADP followed. Reaction mixtures were then extracted with n-hexane, and organic phases removed and dried under argon. The dried organic phases were then separately dissolved in ethanol and aliquots were analyzed on a normal phase silica HPLC column developed with n-hexane containing 4% dioxane at 1 ml per minute. See Saari et al. J. Biol. Chem. 257:13329-13333 (1982). Effluent was monitored at 330 nm. Under these conditions, 11-cis-retinaldehyde and 11-cis retinal eluted at 7 minutes and 22.5 minutes, respectively, and all-trans-retinaldehyde and all-trans retinal eluted at 8 minutes and 23 minutes, respectively.

As indicated in FIG. 8B, the aforementioned HPLC analysis shows that fractions from transfected cells containing p32 expressed 11-cis-retinol dehydrogenase protein which was active in the presence of NAD+, as indicated by the formation of 11-cis-retinaldehyde. A second peak in the chromatogram is all-trans retinaldehyde; however, control incubations with 11-cis retinaldehyde, in the absence of cellular membranes, show that, under the test procedure employed, a large amount of 11-cis retinaldehyde isomerizes to all-trans retinaldehyde. This indicates that the appearance of all-trans retinaldehyde is due to its generation during the incubation process used and extraction procedures, and is not an enzymatic reaction product. Further, incubations with all-trans retinal with cells containing p32 verify the stereo specificity of the enzyme, as no significant formation of all-trans retinaldehyde is detected.

As shown in FIG. 8C, p32 is not enzymatically active in the presence of cofactor NADP.

In FIG. 8D assays of the control cells not expressing p32 show that these do not oxidize 11-cis-retinol into 11-cis-retinaldehyde.

Therefore, the above shows conclusively that p32 is a stereo specific 11-cis-retinol dehydrogenase, which relies on NAD+ as its cofactor.

EXAMPLE 11

Following the work described supra, using bovine materials, additional experiments were carried out to isolate and to clone a human sequence.

A cDNA library from human eye, in λgt11 was purchased from a commercial supplier (i.e., Clontech). The bovine cDNA described supra, i.e., SEQ ID NO: 10, was used as a probe. The cDNA was ³² [P] dCTP labelled by random priming to a high specific activity (about 10₉ cpm/μg of DNA).

The labelled bovine cDNA was then used to probe the human cDNA library. Conditions were as follows: hybridization in 6× SSC, 0.5% SDS, 5× Denhardt's solution, 25% formamide, at 68° C., with 100 μ/ml of salmon sperm DNA, followed by four washes of 2× SSC, 0.5% SDS, at 65° C., for 30 minutes each, and then a final wash at 2× SSC at 42° C. for 30 minutes.

When a positive cDNA was found, the insert (i.e., the cDNA), was excised following the manufacturer's instructions, and then subcloned into the commercially available vector pBluescript. The sequence of the insert was then determined, using well known methods. The sequence of 1128 nucleotides is set forth at SEQ ID NO: 14. The corresponding amino acid sequence of 318 residues is se forth in SEQ ID NO:15.

EXAMPLE 12

In further experiments, the information described in example 11, supra, was used to study and to analyze bovine neuroretina and murine 10 day embryos. Murine embryos were used because, apart from the general usefulness of the system for studying developmental biology, retinol dehydrogenases are extremely active in development. The model is extrapolatable to human development.

RNA (5-10 μg), was isolated from bovine neuroretinas, or from murine 10 day embryos, using well known techniques. The RNA was mixed in 4 μl of 5× AMVRT buffer, together with 4 μl of dNTPs from 5 mM stock solutions, 2 μl of oligo dT (18mer, at a final concentration of 10 μM), together with 0.5 μl RNAse inhibitor, and 2μl of avian myelostosis virus reverse transcriptase (10U). The final volume was 20 μl. This resulting mixture was incubated at 42° C. for 30 minutes, and then left on ice until used.

PCR was then carried out. In the PCR, two μl of cDNA were used. Primers were designed on the basis of the deduced amino acid sequence for bovine cDNA set forth supra. The following conserved amino acid sequences were noted:

A) Cys Asp Ser Gly Phe Gly

B) Pro Gly Trp Asp Ala

C) Glu Ala Phe Ser Asp

D) His Pro Arg Thr

"A" corresponds to amino acids 36-41 of SEQ ID NO:12. "B" is found at amino acids 283-287 of this sequence. "C" is found at positions 183-187, and "D" at positions 276-279. "Conserved" as used herein refers to conseryation between the deduced sequence, the sequence for liver RDH shown by Chai, et al. J. Biol. Chem 270: 3900-3904 (1995), incorporated by reference in its entirety, and Simon, et al, J. Biol. Chem 270: 1107-1112 (1995), also incorporated by reference.

Degenerate oligomers were prepared. In a first set of PCR experiments, degenerate oligos based upon A and B were used as primers, i.e.:

     3' A C G T G A A T T C T G Y G A Y T C N G G N W T Y G G                                                             (SEQ ID NO:16)                           3' A C G T G A A T T C T T N G C R T C C C C A N C C                                                                 (SEQ ID NO:17)                     

as forward and reverse primers respectively. The primers were mixed with the two μl of cDNA discussed supra. Conditions were 1 minute of denaturation at 94° C., 1 minute of annealing at 50° C., and two minutes at 72° C., for elongation. This constituted 1 cycle. Twenty-five cycles were carried out.

Following the first PCR, 5 μl samples of PCR product were combined with primers based upon "C" and "D," i.e.:

     3' (SEQ ID NO:18)T T C G A R G C N T T Y T C N G A                             3' (SEQ ID NO:19)T T C C G N G T N C K N G G R T G                       

as forward and reverse primers, respectively. Conditions were exactly as used in the first set of experiments, except that the annealing temperature was 55° C.

Reaction products were analyzed on 1.5% agarose gels with ethidium bromide. The assumption was that the amplification products should be about 300 base pairs in length. As such, any 300 base pair bands visualized confirmed that the PCR protocol generated products of appropriate size. The experiments were repeated, using 1% low melting point agarose gels, and the PCR products were eluted therefrom. The isolated products were reamplified, using the same protocols, and were cloned into plasmids (TA cloning kit, Invitrogen). The plasmid DNA was prepared from transformants using standard protocols, and then analyzed by restriction digestion, using EcoRI. Any inserts of about 300 base pairs were analyzed further, using vector specific primers. The PCR products are presented in SEQ ID NOS: 20-23 with deduced amino acid sequences being presented as SEQ ID NOS: 24-27. SEQ ID NOS: 20 and 24 correspond to bovine sequences, while all others are murine sequences. In these nucleotide sequences, the first base ("C") is an artifact of the experiment, resulting from cleavage by a restriction endonuclease. Hence, one begins with the second nucleotide base in determining the deduced amino acid sequence. Further, note that sequences corresponding to the degenerate oligos, which would normally be included at the 5' and 3' termini, are not included.

EXAMPLE 13

The PCR product set forth in SEQ ID NO: 19 was then used in further probing experiments.

A murine 8.5 day cDNA library (in λgt10), was screened, using randomly labelled SEQ ID NO: 22, where the hybridization took place in 6× SSC, 0.5% SDS, 5× Denhardts's solution, 50% formamide at 42° C., with 100 μg/ml of salmon sperm DNA, followed by one wash at 2× SSC, 0.5% SDS at 50° C. for 30 minutes. A positive cDNA clone was identified, subcloned into pBluescript, and sequenced. The nucleotide sequence, and deduced amino acid sequence, are set forth as SEQ ID NOS: 28 and 29.

EXAMPLE 14

Following the work described, supra, the human cDNA was used to probe a human genomic library. The probe was prepared by PCR and randomly labelled as described sura.

The primers used in the PCR were derived from the cDNA sequence of SEQ ID NO:11 and were as follows:

Forward primer:

5'-G C T T C G G G C G C T G T A G T A-3' (SEQ ID NO:30) and

Reverse Primer:

5'-A A A A C A A T C T C T T G C T G G A A-3'" (SEQ ID NO:31)

PCR was carried out by denaturing at 95° C., followed by annealing at 55° C., and elongation at 72° C. 2-5U of Taq polymerase and 0.2 μM of each primer were used. Thirty cycles were carried out.

The amplified fragment of 1056 bp was isolated, following agarose gel electrophoresis analysis and cloned into vector PCR (commercially available from Invitrogen). This probe was used to screen a human genomic library in λFXII vector, from Stratagene. The manufacturer's instructions were followed to screen approximately 1×10⁶ plaque forming units. 10₆ cpm/ml of hybridization solution was used. Hybridization was carried out overnight with 6× SSC, 0.5% SDS, 5× Denhardt's solution, 50% formamide at 42° C., with 100 μg/ml of salmon sperm DNA, followed by one wash at 1× SSC, 0.1% SDS at 50° C. and a final wash at 0.5× SSC, 0.1% SDS at 650° C. Each wash was for 30 minutes. Several positive plaques were isolated, rescreened, and λDNA prepared, using the glycerol step gradient method described by Sambrook et al. Molecular Cloning, A Laboratory Manual (2d edition, 1989), incorporated by reference.

The isolated genomic clones were sequenced by analyzing fragments obtained following PCR reactions, using 100 mg of genomic λ clones per reaction as templates. To carry out the PCR, different primers, derived from the cDNA sequence of SEQ ID NO:11 were used in two PCR reactions, numbered `one` and `two`.

Specifically, the primers used in PCR reaction one were

SEQ ID NO:30, supra (forward primer) and

5'-C T C A G G C T G T C A G A G A A G G C C T-3'

(SEQ ID NO:32) (reverse primer)

The primers used in PCR reaction two were

5'-G A C G A T T T C C A G C G G G T G C-3'

(SEQ ID NO:33) (forward primer) and

SEQ ID NO:31, supra

PCR was carried out by denaturing at 95° C., followed by annealing at 55° C. and elongation at 72° C. 2-5U of Taq polymerase and 0.2 μM of each primer was used. Thirty cycles were carried out. The amplified fragments from reactions one and two, were 2.2 kb and 2.5 kb respectively. Each fragment was cloned into vector PCR commercially available from Invitrogen.

Sequence analysis of the cloned fragments using vector specific primers or internal primers, permitted identification of exon-intron boundaries.

The structure of the gene is presented in FIG. 9.

EXAMPLE 15

Studies were carried out to identify the location of the gene on chromosomes.

To do this, high molecular weight DNA was isolated from human leuckoytes, Chinese hamster cells, murine liver cells, and from hamster/human and mouse/human somatic hybrid cell lines. These hybrid cell lines each retained one human chromosome, as well as rodent genomes.

The isolated DNA was digested with Hind III, fractionated on agarose gel via electrophoresis, and then transferred to a nylon filter. These were then probed, using the human cDNA described supra, labelled as described supra.

Slides of chromosomes were prepared from lymphocyte cultures, using art recognized techniques. The λDNA from 3 genomic clones were mixed and labelled with biotinylated 16-dUTP, by Nick translation. A centromere specific probe for human chromosome 12 centromere (obtained from the ATCC, under Accession Number D12Z1), was labelled with fluoro-red-dUTP, following the manufacturer's instructions. Pre-annealing of the probes, pretreatment of the slides, hybridization conditions, signal amplification, and detection, were in accordance with well known techniques. Chromosomes were counter-stained with 4,6 diamino-2-phenyl indole (DAPI), and signal was visualized using a fluorescence microscope.

Analysis of all of these data indicated that the gene for human 11-cis RDH spans more than 4 kilobases, and is divided into 4 coding exons, which range from 165 to 342 base pairs in length. Further, an exon was found in the 5 untranslated region, and the length of the last coding exon has not been established. Introns range in size from 250 base pairs to 1.9 kilobases. FIG. 9 shows this schematically.

Study of exon/intron boundaries showed that all splice donor and acceptor sites follow the well known, canonical GT/AG rule. The Initiation codon and the conserved cofactor binding site are encoded by exon 2, while the active site, with invariant tyrosine residue, is encoded by exon 3. The gene for human 11-cis maps to chromosome 12q13-14.

As shown above, this invention provides a method for the isolation and characterization of a novel protein, p32, which associates with the p63 of RPE. The primary structure of p32 demonstrates that it has all the critical features of a functional short-chain alcohol dehydrogenase including a putative cofactor binding site and essential residues involved in the catalytic mechanism, namely the almost invariant tyrosine containing sequence motif Y-X-X-X-K (Persson et al., Eur. J. Biochem. 200:537-543 (1991)). The restricted tissue expression and the abundance of p32 in RPE indicates that this protein carries out a function which is unique to the RPE. This possibility, and the fact that it forms a complex with p63 which previously has been shown to be a component of the retinoid uptake machinery in RPE-cells (Bavik, et al., J. Biol. Chem. 267:23035-23042 (1992)), shows that the substrate for p32 is a retinoid.

A major metabolic step in retinoid metabolism in RPE-cells is the conversion of 11-cis retinol to 11-cis retinaldehyde. Based on the results obtained hereinabove showing the restricted expression of p32 in the RPE, and the particular biochemical properties of this protein further investigation confirmed that p32 is in fact an 11-cis-retinol dehydrogenase, the enzyme which catalyzes this reaction.

One aspect of the invention is the ability to produce recombinant 11-cis-retinol dehydrogenase. The recombinant enzyme can be used to produce 11-cis-retinaldehyde in levels higher, and in purer form, than would be,available using standard biochemical methodologies. Thus, the isolated nucleic acid molecules of the invention, which include SEQ ID NOS: 10, 14, 20-23, 28 and 29, as well as sequences which have complements which hybridize to the listed sequences, under stringent conditions as well as those nucleic acid molecules which hybridize to SEQ ID NO: 10 under stringent conditions can be used in this context. By the term "stringent conditions" is meant hybridization in 6× SSC, 0.5% SDS, 5× Denhardt's solution at 68° C., with 100 ug/ml of salmon sperm DNA, and a final wash with 0.5-1.0× SSC at 50° C. The term is also used herein to refer to any set of parameters which are at least as stringent as those set forth above. As is well known, equally stringent conditions can be created by changing one parameter to make it less stringent, with another parameter being changed to increase its stringency. Thus, any nucleic acid molecule which fulfills the hybridization criteria set forth herein will be expected to code for p32 or a p32 homologue. These nucleic acid molecules preferably encode mammalian retinol dehydrogenases, such as 11-cis-retinol dehydrogenase. Exemplary, but by no means the only mammalian species included, are human, bovine and murine enzymes. The enzyme may be produced in an in vitro system, such as the one described above, or via transfecting or transforming eukaryotic or prokaryotic cell lines, such as CHO and COS cells or bacterial strains such as E. coli or the yeast strain S.cervisiae with the nucleic acid molecules of the invention. In an especially preferred embodiment, the nucleic acid molecules are contained within an expression vector, operably linked to a promoter. Complementary DNA, or "cDNA" is preferred, but genomic DNA and mRNA can also be used.

The identification of the p32, 11-cis retinol dehydrogenase, as a member of the short-chain alcohol dehydrogenase superfamily is important in view of the retinoid-metabolism which occurs in non-ocular tissues. Studies show that generation of all-trans retinoic acid from all-trans retinol is carried out in a two step process (Posch et al., Biochemistry 30:6224-6230 (1991)). First, retinol is oxidized to retinal by a membrane bound retinol dehydrogenase. In a second step, the retinal is oxidized to retinoic acid. Thus, the oxidation of retinol into retinal, occurring in non-ocular tissues, is similar to the reaction carried out during synthesis of 11-cis retinal from 11-cis retinol in the visual cycle. In light of these similarities, it can be proposed that formation of all-trans retinal from all-trans retinol is carried out by an enzyme which is structurally similar to the p32 11-cis retinol dehydrogenase isolated by this invention. These findings are surprising in contrast to presently held views as it is generally believed that this metabolic step is carried out by members of the medium chain alcohol dehydrogenases. See Duester, Alcohol Clin. Exp. Res. 15:568-572 (1991); Yang et al., Alcohol Clin. Exp. Res. 17:496 (1993) and Zgombic-Knight et al., J. Biol. Chem. 269:6790-6795 (1994). Thus the identification and structural characterization of the p32 11-cis retinol dehydrogenase, provided by this invention also provides a previously unexpected avenue for the isolation and characterization of similar dehydrogenases involved in retinol metabolism is non-ocular tissues.

The p32 protein and nucleic acid encoding therefor and other aspects of this invention are also useful in many other important applications. For example, as it has been shown that p32 is part of an oligomeric protein complex which functions as a membrane receptor for RBP in RPE-cells, the nucleic acid sequence coding for p32 can be used in a phenotypic/genic diagnostic analysis to determine retinoid accumulation, which can lead to retinitis pigmentosa.

Additionally, as shown, p32 possesses 11-cis-retinol dehydrogenase activity, which catalyzes the conversion of 11-cis retinol to 11-cis-retinaldehyde, a major metabolic step in retinoid metabolism in RPE-cells carried out by a membrane bound dehydrogenase. Thus, retinoid accumulation may be directly or indirectly tied to the presence of p32 and/or its activation or inhibition, for example, its complex formation with the RBP receptor p63.

In other applications the effect of potential retinoid drugs for treatment of various diseases on the 11-cis-retinal dehydrogenase activity of p32 may be assayed as such drugs may adversely effect the enzyme, and to thus determine which of the different drugs have limited or no adverse effect on enzyme activity.

Examples of such diseases include those of the eye and also skin disorders such as psoriasis and acne. Certain cancers such as T-cell leukemias may also be tested by retinoid drugs and hence be candidates for assaying p32 activity.

The various known functions of retinoids also suggests that various other retinoid linked pathological conditions may be diagnosed via assays for levels of the p63/p32 receptor complex associated with a particular retinol binding protein. Art recognized techniques may be used, such a immunoassays, and so forth, to determine whether p63/p32 receptor complex levels are too low or too high--i.e., are at variance with a normal level.

Further, as p32 complexes with the p63 component of the retinoid uptake machinery in RPE cells, it may also be used in a therapeutic context, as it is well known that soluble receptors may be used to prevent binding of a protein to its membrane-linked receptor. Thus, a subject characterized by enhanced levels of production of retinol binding protein may be treated via administering an amount of soluble receptor complex or antibody sufficient to inhibit binding of the retinol binding protein or other related molecule to its target, namely, an inhibitor of p32's retinol dehydrogenase activity. Other aspects of the invention will be clear to the skilled artisan and need not be repeated here.

In yet another application, monoclonal and polyclonal antibodies to p32 can be generated, which are useful, inter alia, in monitoring the instance of pathological conditions characterized by aberrant levels of a receptor for retinol binding protein, by binding analysis of the antibody with body fluid or tissue samples. The generation of antibodies to p32 can be accomplished, for example, by using the procedure set out in Bavik et al., J. Biol. Chem. 268:20540-20546 (1993) for the generation of antibodies to p63, including mAb A52.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.

As shown above, this invention provides a method for the isolation and characterization of a novel protein, p32, which associates with the p63 of RPE. The primary structure of p32 demonstrates that it has all the critical features of a functional short-chain alcohol dehydrogenase including a putative cofactor binding site and essential residues involved in the catalytic mechanism, namely the almost invariant tyrosine containing sequence motif Y-X-X-X-K (Persson et al., Eur. J. Biochem. 200:537-543 (1991)). The restricted tissue expression and the abundance of p32 in RPE indicates that this protein carries out a function which is unique to the RPE. This possibility, and the fact that it forms a complex with p63 which previously has been shown to be a component of the retinoid uptake machinery in RPE-cells (Bavik, et al., J. Biol. Chem. 267:23035-23042 (1992)), shows that the substrate for p32 is a retinoid.

A major metabolic step in retinoid metabolism in RPE-cells is the conversion of 11-cis retinol to 11-cis retinaldehyde. Based on the results obtained hereinabove showing the restricted expression of p32 in the RPE, and the particular biochemical properties of this protein further investigation confirmed that p32 is in fact an 11-cis-retinol dehydrogenase, the enzyme which catalyzes this reaction.

    __________________________________________________________________________     #             SEQUENCE LISTING                                                 - (1) GENERAL INFORMATION:                                                     -    (iii) NUMBER OF SEQUENCES:  31                                            - (2) INFORMATION FOR SEQ ID NO: 1:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 18 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              #1:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Leu Val Glu Ala Val Leu Ala Glu Val Leu Pr - #o Lys Pro Ala Gln Thr          #                 15                                                           - Val Ala                                                                      - (2) INFORMATION FOR SEQ ID NO: 2:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 8 amino                                                            (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              #2:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Tyr Ser Pro Gly Trp Asp Ala Lys                                                              5                                                              - (2) INFORMATION FOR SEQ ID NO: 3:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 15 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              #3:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Thr Pro Val Thr Asn Leu Glu Thr Leu Glu As - #p Thr Leu Gln Ala              #                 15                                                           - (2) INFORMATION FOR SEQ ID NO: 4:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 7 amino                                                            (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              #4:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Asp Val Ala Pro Phe Gly Val                                                                  5                                                              - (2) INFORMATION FOR SEQ ID NO: 5:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 14 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              #5:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Leu His Thr Thr Leu Leu Asp Val Thr Asp Pr - #o Gln Ser Ile                  #                 10                                                           - (2) INFORMATION FOR SEQ ID NO: 6:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 23 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         #6:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    #                23ARGC NGT                                                    - (2) INFORMATION FOR SEQ ID NO: 7:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 27 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         #7:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    #             27   TGNG CNGGYTT                                                - (2) INFORMATION FOR SEQ ID NO: 8:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 24 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         #8:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    #                24ACNA AYYT                                                   - (2) INFORMATION FOR SEQ ID NO: 9:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 27 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         #9:   (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    #             27   ARNG TRTCYTC                                                - (2) INFORMATION FOR SEQ ID NO: 10:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 1122 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -     (ix) FEATURE:                                                            #retinol dehydrogenase: p32;11-cis                                             -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                 #CCT CTG CAG        53C ACCTGGGCTC CAGCC ATG TGG CTG                           #   Met Trp Leu Pro Leu Leu                                                    # 5                                                                            - TGC CTG CTG CTG GGT GTC TTG CTC TGG GCA GC - #A CTG TGG TTG CTC AGG           101                                                                           Leu Gly Val Leu Leu Trp Ala Ala Leu Trp Le - #u Leu Arg Asp Arg Gln            #            20                                                                - GAC CGG CCA GCC AGC GAT GCC TTT ATC TTC AT - #C ACC GGC TGT GAC TCG           149                                                                           Cys Leu Pro Ala Ser Asp Ala Phe Ile Phe Il - #e Thr Gly Cys Asp Ser            #        35                                                                    - GGC TTT GGG CGG CTC CTT GCT CTG AGG CTG GA - #C CAG AGA GGC TTC CGA           197                                                                           Gly Phe Gly Arg Leu Leu Ala Leu Arg Leu As - #p Gln Arg Gly Phe Arg            #    50                                                                        - GTA CTG GCC AGC TGC CTG ACA CCC TCG GGG GC - #G GAG GAC CTC CAG CGG           245                                                                           Val Leu Ala Ser Cys Leu Thr Pro Ser Gly Al - #a Glu Asp Leu Gln Arg            #70                                                                            - GTC GCC TCC TCC CGC CTC CAC ACC ACC CTG CT - #G GAT GTC ACA GAT CCC           293                                                                           Val Ala Ser Ser Arg Leu His Thr Thr Leu Le - #u Asp Val Thr Asp Pro            #                85                                                            - CAG AGC ATC CGG CAG GCA GTC AAG TGG GTG GA - #A ACG CAT GTT GGG GAA           341                                                                           Gln Ser Ile Arg Gln Ala Val Lys Trp Val Gl - #u Thr His Val Gly Glu            #            100                                                               - GCA GGG CTT TTT GGT CTG GTG AAT AAT GCT GG - #T GTG GCT GGC ATC ATT           389                                                                           Ala Gly Leu Phe Gly Leu Val Asn Asn Ala Gl - #y Val Ala Gly Ile Ile            #       115                                                                    - GGT CCC ACC CCA TGG CAG ACG CGG GAG GAC TT - #C CAG CGG GTG CTG AAT           437                                                                           Gly Pro Thr Pro Trp Gln Thr Arg Glu Asp Ph - #e Gln Arg Val Leu Asn            #   130                                                                        - GTG AAC ACG CTG GGT CCC ATC GGG GTC ACC CT - #C GCC CTG CTG CCC CTG           485                                                                           Val Asn Thr Leu Gly Pro Ile Gly Val Thr Le - #u Ala Leu Leu Pro Leu            135                 1 - #40                 1 - #45                 1 -        #50                                                                            - CTG CTG CAG GCC CGG GGC CGA GTG ATC AAC AT - #C ACC AGT GTC CTT GGC           533                                                                           Leu Leu Gln Ala Arg Gly Arg Val Ile Asn Il - #e Thr Ser Val Leu Gly            #               165                                                            - CGT CTG GCA GCC AAT GGA GGG GGC TAC TGC GT - #C TCC AAG TTT GGC CTG           581                                                                           Arg Leu Ala Ala Asn Gly Gly Gly Tyr Cys Va - #l Ser Lys Phe Gly Leu            #           180                                                                - GAG GCC TTC TCT GAC AGC CTG AGG CGA GAT GT - #G GCT CCT TTT GGG GTA           629                                                                           Glu Ala Phe Ser Asp Ser Leu Arg Arg Asp Va - #l Ala Pro Phe Gly Val            #       195                                                                    - CGG GTC TCT ATC GTG GAA CCT GGC TTC TTC CG - #A ACC CCT GTG ACA AAC           677                                                                           Arg Val Ser Ile Val Glu Pro Gly Phe Phe Ar - #g Thr Pro Val Thr Asn            #   210                                                                        - CTG GAA ACT TTG GAG GAC ACC CTG CAG GCC TG - #C TGG GCA CGG CTG CCT           725                                                                           Leu Glu Thr Leu Glu Asp Thr Leu Gln Ala Cy - #s Trp Ala Arg Leu Pro            215                 2 - #20                 2 - #25                 2 -        #30                                                                            - CCA GCC ACA CAG GCC CTC TAT GGG GAG GCC TT - #C CTC ACC AAA TAC CTG           773                                                                           Pro Ala Thr Gln Ala Leu Tyr Gly Glu Ala Ph - #e Leu Thr Lys Tyr Leu            #               245                                                            - AGA GTG CAG CAA CGT ATC ATG AAC ATG ATC TG - #T GAT CCG GAC CTG GCC           821                                                                           Arg Val Gln Gln Arg Ile Met Asn Met Ile Cy - #s Asp Pro Asp Leu Ala            #           260                                                                - AAG GTG AGC AGG TGC CTG GAG CAT GCC CTA AC - #T GCC CGT CAC CCC AGA           869                                                                           Lys Val Ser Arg Cys Leu Glu His Ala Leu Th - #r Ala Arg His Pro Arg            #       275                                                                    - ACC CGC TAC AGC CCA GGC TGG GAT GCC AAG CT - #G CTC TGG TTG CCA GCC           917                                                                           Thr Arg Tyr Ser Pro Gly Trp Asp Ala Lys Le - #u Leu Trp Leu Pro Ala            #   290                                                                        - TCC TAC TTG CCA GCC AGG CTG GTG GAT GCT GT - #G CTC GCC TGG GTC CTT           965                                                                           Ser Tyr Leu Pro Ala Arg Leu Val Asp Ala Va - #l Leu Ala Trp Val Leu            295                 3 - #00                 3 - #05                 3 -        #10                                                                            - CCC AAG CCT GCC CAG ACA GTC TAC TAA ATCCAGCCC - #T CCAGCAAAAG                1012                                                                           Pro Lys Pro Ala Gln Thr Val Tyr                                                                315                                                            - ATGGTTGTTC AAGGCAAGGA CTCTGATTTA TTCTGTCCCC TACCCTGGTA CT - #GCCTGGTG        1072                                                                           #            1122GTCACT CAATAAATGT ATTATTCAAA ACAAAAAAAA                       - (2) INFORMATION FOR SEQ ID NO: 11:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 344 amino                                                          (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY: Rat D-b-h - #ydroxybutyrate dehydrogenase (rBDH)       -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                 - Met Met Leu Ala Ala Arg Leu Ser Arg Pro Le - #u Ser Gln Leu Pro Gly          #                 15                                                           - Lys Ala Leu Ser Val Cys Asp Arg Glu Asn Gl - #y Thr Arg His Thr Leu          #            30                                                                - Leu Phe Tyr Pro Ala Ser Phe Ser Pro Asp Th - #r Arg Arg Thr Tyr Thr          #        45                                                                    - Ser Gln Ala Asp Ala Ala Ser Gly Lys Ala Va - #l Leu Val Thr Gly Cys          #    60                                                                        - Asp Ser Gly Phe Gly Phe Ser Leu Ala Lys Hi - #s Leu His Ser Lys Gly          #80                                                                            - Phe Leu Val Phe Ala Gly Cys Leu Leu Lys Gl - #u Gln Gly Asp Ala Gly          #                95                                                            - Val Arg Glu Leu Asp Ser Leu Lys Ser Asp Ar - #g Leu Arg Thr Ile Gln          #           110                                                                - Leu Asn Val Cys Asn Ser Glu Glu Val Glu Ly - #s Ala Val Glu Thr Val          #       125                                                                    - Arg Ser Gly Leu Lys Asp Pro Glu Lys Gly Me - #t Trp Gly Leu Val Asn          #   140                                                                        - Asn Ala Gly Ile Ser Thr Phe Gly Glu Val Gl - #u Phe Thr Ser Met Glu          145                 1 - #50                 1 - #55                 1 -        #60                                                                            - Thr Tyr Lys Glu Val Ala Glu Val Asn Leu Tr - #p Gly Thr Val Arg Thr          #               175                                                            - Thr Lys Ser Phe Leu Pro Leu Leu Arg Arg Al - #a Lys Gly Arg Val Val          #           190                                                                - Asn Ile Ser Ser Met Leu Gly Arg Met Ala As - #n Pro Ala Arg Ser Pro          #       205                                                                    - Tyr Cys Ile Thr Lys Phe Gly Val Glu Ala Ph - #e Ser Asp Cys Leu Arg          #   220                                                                        - Tyr Glu Met His Pro Leu Gly Val Lys Val Se - #r Val Val Glu Pro Gly          225                 2 - #30                 2 - #35                 2 -        #40                                                                            - Asn Phe Ile Ala Ala Thr Ser Leu Tyr Ser Pr - #o Glu Arg Ile Gln Ala          #               255                                                            - Ile Ala Lys Lys Met Trp Asp Glu Leu Pro Gl - #u Val Val Arg Lys Asp          #           270                                                                - Tyr Gly Lys Lys Tyr Phe Asp Glu Lys Ile Al - #a Lys Met Glu Thr Tyr          #       285                                                                    - Cys Asn Ser Gly Ser Thr Asp Thr Ser Ser Va - #l Ile Asn Ala Val Thr          #   300                                                                        - His Ala Leu Thr Ala Ala Thr Pro Tyr Thr Ar - #g Tyr His Pro Met Asp          305                 3 - #10                 3 - #15                 3 -        #20                                                                            - Tyr Tyr Trp Trp Leu Arg Met Gln Val Met Th - #r His Phe Pro Gly Ala          #               335                                                            - Ile Ser Asp Lys Ile Tyr Ile His                                                          340                                                                - (2) INFORMATION FOR SEQ ID NO: 12:                                           -      (i) SEQUENCE CHARACTERISTICS:                                                     (A) LENGTH:  327 ami - #no acids                                               (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY: Human est - #radiol 17-b dehydrogenase (hEDH)          -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                 - Ala Arg Thr Val Val Leu Ile Thr Gly Cys Se - #r Ser Gly Ile Gly Leu          #                 15                                                           - His Leu Ala Val Arg Leu Ala Ser Asp Pro Se - #r Gln Ser Phe Lys Val          #            30                                                                - Tyr Ala Thr Leu Arg Asp Leu Lys Thr Gln Gl - #y Arg Leu Trp Glu Ala          #        45                                                                    - Ala Arg Ala Leu Ala Cys Pro Pro Gly Ser Le - #u Glu Thr Leu Gln Leu          #    60                                                                        - Asp Val Arg Asp Ser Lys Ser Val Ala Ala Al - #a Arg Glu Arg Val Thr          #80                                                                            - Glu Gly Arg Val Asp Val Leu Val Cys Asn Al - #a Gly Leu Gly Leu Leu          #                95                                                            - Gly Pro Leu Glu Ala Leu Gly Glu Asp Ala Va - #l Ala Ser Val Leu Asp          #           110                                                                - Val Asn Val Val Gly Thr Val Arg Met Leu Gl - #n Ala Phe Leu Pro Asp          #       125                                                                    - Met Lys Arg Arg Gly Ser Gly Arg Val Leu Va - #l Thr Gly Ser Val Gly          #   140                                                                        - Gly Leu Met Gly Leu Pro Phe Asn Asp Val Ty - #r Cys Ala Ser Lys Phe          145                 1 - #50                 1 - #55                 1 -        #60                                                                            - Ala Leu Glu Gly Leu Cys Glu Ser Leu Ala Va - #l Leu Leu Leu Pro Phe          #               175                                                            - Gly Val His Leu Ser Leu Ile Glu Cys Gly Pr - #o Val His Thr Ala Phe          #           190                                                                - Met Glu Lys Val Leu Gly Ser Pro Glu Glu Va - #l Leu Asp Arg Thr Asp          #       205                                                                    - Ile His Thr Phe His Arg Phe Tyr Gln Tyr Le - #u Ala His Ser Lys Gln          #   220                                                                        - Val Phe Arg Glu Ala Ala Gln Asn Pro Glu Gl - #u Val Ala Glu Val Phe          225                 2 - #30                 2 - #35                 2 -        #40                                                                            - Leu Thr Ala Leu Arg Ala Pro Lys Pro Thr Le - #u Arg Tyr Phe Thr Thr          #               255                                                            - Glu Arg Phe Leu Pro Leu Leu Arg Met Arg Le - #u Asp Asp Pro Ser Gly          #           270                                                                - Ser Asn Tyr Val Thr Ala Met His Arg Glu Va - #l Phe Gly Asp Val Pro          #       285                                                                    - Ala Lys Ala Glu Ala Gly Ala Glu Ala Gly Gl - #y Gly Ala Gly Pro Gly          #   300                                                                        - Ala Glu Asp Glu Ala Gly Arg Ser Ala Val Gl - #y Asp Pro Glu Leu Gly          305                 3 - #10                 3 - #15                 3 -        #20                                                                            - Asp Pro Pro Ala Ala Pro Gln                                                                  325                                                            - (2) INFORMATION FOR SEQ ID NO: 13:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 244 amino                                                          (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY:E.coli 3-oxoa - #cyl[acyl carrier protein]reductase               (FABG)                                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                                 - Met Asn Phe Glu Gly Lys Ile Ala Leu Val Th - #r Gly Ala Ser Arg Gly          #                 15                                                           - Ile Gly Arg Ala Ile Ala Glu Thr Leu Ala Al - #a Arg Gly Gly Lys Val          #            30                                                                - Ile Gly Thr Ala Thr Ser Glu Asn Gly Ala Gl - #n Ala Ile Ser Asp Tyr          #        45                                                                    - Leu Gly Ala Asn Gly Lys Gly Leu Met Leu As - #n Val Thr Asp Pro Ala          #    60                                                                        - Ser Ile Glu Ser Val Leu Glu Lys Ile Arg Al - #a Glu Phe Gly Glu Val          #80                                                                            - Asp Ile Leu Val Asn Asn Ala Gly Ile Thr Ar - #g Asp Asn Leu Leu Met          #                95                                                            - Arg Met Lys Asp Glu Glu Trp Asn Asp Ile Il - #e Glu Thr Asn Leu Ser          #           110                                                                - Ser Val Phe Arg Leu Ser Lys Ala Val Met Ar - #g Ala Met Met Lys Lys          #       125                                                                    - Arg His Gly Arg Ile Ile Thr Ile Gly Ser Va - #l Val Gly Thr Met Gly          #   140                                                                        - Asn Gly Gly Gln Ala Asn Tyr Ala Ala Ala Ly - #s Ala Gly Leu Ile Gly          145                 1 - #50                 1 - #55                 1 -        #60                                                                            - Phe Ser Lys Ser Leu Ala Arg Glu Val Ala Se - #r Arg Gly Ile Thr Val          #               175                                                            - Asn Val Val Ala Pro Gly Phe Ile Glu Thr As - #p Met Thr Arg Ala Leu          #           190                                                                - Ser Asp Asp Gln Arg Ala Gly Ile Leu Ala Gl - #n Val Pro Ala Gly Arg          #       205                                                                    - Leu Gly Gly Ala Gln Glu Ile Ala Asn Ala Va - #l Ala Phe Leu Ala Ser          #   220                                                                        - Asp Glu Ala Ala Tyr Ile Thr Gly Glu Thr Le - #u His Val Asn Gly Gly          225                 2 - #30                 2 - #35                 2 -        #40                                                                            - Met Tyr Met Val                                                              - (2) INFORMATION FOR SEQ ID NO: 14:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 1128 base                                                          (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: human 11- - #cis retinol dehydrogenase                 #14:  (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - TAAGCTTCGG GCGCTGTAGT ACCTGCCAGC TTTCGCCACA GGAGGCTGCC AC - #CTGTAGGT          60                                                                           - CACTTGGGCT CCAGCTATGT GGCTGCCTCT TCTGCTGGGT GCCTTACTCT GG - #GCAGTGCT         120                                                                           - GTGGTTGCTC AGGGACCGGC AGAGCCTGCC CGCCAGCAAT GCCTTTGTCT TC - #ATCACCGG         180                                                                           - CTGTGACTCA GGCTTTGGGC GCCTTCTGGC ACTGCAGCTG GACCAGAGAG GC - #TTCCGAGT         240                                                                           - CCTGGCCAGC TGCCTGACCC CCTCCGGGGC CGAGGACCTG CAGCGGGTGG CC - #TCCTCCCG         300                                                                           - CCTCCACACC ACCCTGTTGG ATATCACTGA TCCCCAGAGC GTCCAGCAGG CA - #GCCAAGTG         360                                                                           - GGTGGAGATG CACGTTAAGG AAGCAGGGCT TTTTGGTCTG GTGAATAATG CT - #GGTGTGGC         420                                                                           - TGGTATCATC GGACCCACAC CATGGCTGAC CCGGGACGAT TTCCAGCGGG TG - #CTGAATGT         480                                                                           - GAACACAATG GGTCCCATCG GGGTCACCCT TGCCCTGCTG CCTCTGCTGC AG - #CAAGCCCG         540                                                                           - GGGCCGGGTG ATCAACATCA CCAGCGTCCT GGGTCGCCTG GCAGCCAATG GT - #GGGGGCTA         600                                                                           - CTGTGTCTCC AAATTTGGCC TGGAGGCCTT CTCTGACAGC CTGAGGCGGG AT - #GTAGCTCA         660                                                                           - TTTTGGGATA CGAGTCTCCA TCGTGGAGCC TGGCTTCTTC CGAACCCCTG TG - #ACCAACCT         720                                                                           - GGAGAGTCTG GAGAAAACCC TGCAGGCCTG CTGGGCACGG CTGCCTCCTG CC - #ACACAGGC         780                                                                           - CCACTATGGG GGGGCCTTCC TCACCAAGTA CCTGAAAATG CAACAGCGCA TC - #ATGAACCT         840                                                                           - GATCTGTGAC CCGGACCTAA CCAAGGTGAG CCGATGCCTG GAGCATGCCC TG - #ACTGCTCG         900                                                                           - ACACCCCCGA ACCCGCTACA GCCCAGGTTG GGATGCCAAG CTGCTCTGGC TG - #CCTGCCTC         960                                                                           - CTACCTGCCA GCCAGCCTGG TGGATGCTGT GCTCACCTGG GTCCTTCCCA AG - #CCTGCCCA        1020                                                                           - AGCAGTCTAC TGAATCCAGC CTTCCAGCAA GAGATTGTTT TTCAAGGACA AG - #GACTTTGA        1080                                                                           #              1128CCCT GGTACTGCCT GGTGCCTGCC ACAAAATA                         - (2) INFORMATION FOR SEQ ID NO: 15:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 318 amino                                                          (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                            #11-cis retinol dehydrogenasen                                                 #15:  (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - Met Trp Leu Pro Leu Leu Leu Gly Ala Leu Le - #u Trp Ala Val Leu Trp          #15                                                                            - Leu Leu Arg Asp Arg Gln Ser Leu Pro Ala Se - #r Asn Ala Phe Val Phe          #             30                                                               - Ile Thr Gly Cys Asp Ser Gly Phe Gly Arg Le - #u Leu Ala Leu Gln Leu          #         45                                                                   - Asp Gln Arg Gly Phe Arg Val Leu Ala Ser Cy - #s Leu Thr Pro Ser Gly          #     60                                                                       - Ala Glu Asp Leu Gln Arg Val Ala Ser Ser Ar - #g Leu His Thr Thr Leu          #80                                                                            - Leu Asp Ile Thr Asp Pro Gln Ser Val Gln Gl - #n Ala Ala Lys Trp Val          #                950                                                           - Glu Met His Val Lys Glu Ala Gly Leu Phe Gl - #y Leu Val Asn Asn Ala          #           110                                                                - Gly Val Ala Gly Ile Ile Gly Pro Thr Pro Tr - #p Leu Thr Arg Asp Asp          #       125                                                                    - Phe Gln Arg Val Leu Asn Val Asn Thr Met Gl - #y Pro Ile Gly Val Thr          #   140                                                                        - Leu Ala Leu Leu Pro Leu Leu Gln Gln Ala Ar - #g Gly Arg Val Ile Asn          145                 1 - #50                 1 - #55                 1 -        #60                                                                            - Ile Thr Ser Val Leu Gly Arg Leu Ala Ala As - #n Gly Gly Gly Tyr Cys          #               175                                                            - Val Ser Lys Phe Gly Leu Glu Ala Phe Ser As - #p Ser Leu Arg Arg Asp          #           190                                                                - Val Ala His Phe Gly Ile Arg Val Ser Ile Va - #l Glu Pro Gly Phe Phe          #       205                                                                    - Arg Thr Pro Val Thr Asn Leu Glu Ser Leu Gl - #u Lys Thr Leu Gln Ala          #   220                                                                        - Cys Trp Ala Arg Leu Pro Pro Ala Thr Gln Al - #a His Tyr Gly Gly Ala          225                 2 - #30                 2 - #35                 2 -        #40                                                                            - Phe Leu Thr Lys Tyr Leu Lys Met Gln Gln Ar - #g Ile Met Asn Leu Ile          #               255                                                            - Cys Asp Pro Asp Leu Thr Lys Val Ser Arg Cy - #s Leu Glu His Ala Leu          #           270                                                                - Thr Ala Arg His Pro Arg Thr Arg Tyr Ser Pr - #o Gly Trp Asp Ala Lys          #       285                                                                    - Leu Leu Trp Leu Pro Ala Ser Tyr Leu Pro Al - #a Ser Leu Val Asp Ala          #   300                                                                        - Val Leu Thr Trp Val Leu Pro Lys Pro Ala Gl - #n Ala Val Tyr                  305                 3 - #10                 3 - #15                            - (2) INFORMATION FOR SEQ ID NO:16:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 27 base                                                            (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR prime - #r                                         -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:                                 #             27   TCNG GNWTYGG                                                - (2) INFORMATION FOR SEQ ID NO:17:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 25 base                                                            (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR prime - #r                                         -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:                                 #               25 TCCC CANCC                                                  - (2) INFORMATION FOR SEQ ID NO:18:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 24 base                                                            (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR prime - #r                                         -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:                                 #                24TTYT CNGA                                                   - (2) INFORMATION FOR SEQ ID NO:19:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 24 base                                                            (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR prime - #r                                         -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:                                 #                24CKNG GRTG                                                   - (2) INFORMATION FOR SEQ ID NO: 20:                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 262 base                                                           (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR clone - # 194                                      #20:  (xi) SEQUENCE DESCRIPTION: SEQ ID NO:                                    - CTCTCTCAGA AGGGAGCTCT CCTACTTCGG AGTGAAGGTG GCTATGATTG AG - #CCTGGTTA          60                                                                           - CTTTGTTACC AATATGACCC AAGATGAGGG TTTTATTGGA TACCTCCAGG CA - #TTGTGGAA         120                                                                           - CCGGGCCAGC CCAGAGCTGA AAGAACTCTA TGGAGAAAAC TTCCCTGCTG AC - #TTCTTGAA         180                                                                           - GACATTGAGT TTACTGAAAC CACGGTGGAC TCAGAATCTG TCCTTGGTGA CC - #GACTGCAT         240                                                                           #                262CCT GC                                                     - (2) INFORMATION FOR SEQ ID NO:21:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 262 base                                                           (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR clone - # 207                                      -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:                                 - CTCCCTCAGG AGGGGGCTCT CCTACTTTGG GGTGAAGGTG GCTATTATAG AG - #CCTGGCTT          60                                                                           - CTTCCTGACC GGTGTGACCA GTAGTGCCAG ATTATGCTCA AATACCCAGA TG - #CTGTGGGA         120                                                                           - CCAGACCAGC TCAGAAATCA GGGAGATCTA TGGCGAGAAG TACCTGGCAT CC - #TATCTGAA         180                                                                           - AAGGCTAAAC GAATTGGACA AGAGGTGCAA CAAGGACCTG TCTTTGGTGA CT - #GACTGCAT         240                                                                           #                262CCT GC                                                     - (2) INFORMATION FOR SEQ ID NO:22:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 265 base                                                           (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR clone - # 200                                      -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:22:                                 - CAGCCTGAGG CGGGACATGG CTCCGTTCGG AGTACAAGTC TCCATTGTGG AG - #CCTGGCTT          60                                                                           - CTTTCGAACC CCTGTGACCA ACCTGGAGAG TCTGGAGAGC ACCCTGAAGG CT - #TGTTGGGC         120                                                                           - CCGGCTACCT CCAGCTATAC AGGCCCACTA CGGGGAGGCC TTCCTCGATA CT - #CATCTTCG         180                                                                           - AGTACAGCGC CGCATCATGA ACCTGATCTG TGACCCAGAA CTAACGAAGG TG - #ACCAGCTG         240                                                                           #              265 ACTG CTCGC                                                  - (2) INFORMATION FOR SEQ ID NO:23:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 265 base                                                           (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: PCR clone - # 215                                      -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:23:                                 - CAGCCTGAGG CGAGATGTGG CTCCTTTTGG GGTACGGGTC TCTATCGTGG AA - #CCTGGCTT          60                                                                           - CTTCCGAACC CCTGTGACAA ACCTGGAAAC TTTGGAGGGC ACCCTGCAGG CC - #TGCTGGGC         120                                                                           - ACGGCTGCCT CCAGCCACAC AGGCCCTCTA TGGGGAGGCC TTCCTCACCA AA - #TACCTGAG         180                                                                           - AGTGCAGCAA CGTATCATGA ACATGATCTG TGATCCGGAC CTGGCCAAGG TG - #AGCAGGTG         240                                                                           #              265 ACTG CCCGT                                                  - (2) INFORMATION FOR SEQ ID NO:24:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 87 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY:  PCR c - #lone 194                                     #:    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:24                                  - Ser Leu Arg Arg Glu Leu Ser Tyr Phe Gly Va - #l Lys Val Ala Met Ile          #10                 1 - #5                                                     - Glu Pro Gly Tyr Phe Val Thr Asn Met Thr Gl - #n Asp Glu Gly Phe Ile          #             30                                                               - Gly Tyr Leu Gln Ala Leu Trp Asn Arg Ala Se - #r Pro Glu Leu Lys Glu          #         45                                                                   - Leu Tyr Gly Glu Asn Phe Pro Ala Asp Phe Le - #u Lys Thr Leu Ser Leu          #    60                                                                        - Leu Lys Pro Arg Trp Thr Gln Asn Leu Ser Le - #u Val Thr Asp Cys Met          #805                                                                           - Glu His Ala Leu Thr Ala Cys                                                                  85                                                             - (2) INFORMATION FOR SEQ ID NO:25:                                            -      (i) SEQUENCE CHARACTERISTICS:                                                     (A) LENGTH:87 amino aci - #ds                                                  (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY:  PCR c - #lone 207                                     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:25:                                 - Ser Leu Arg Arg Gly Leu Ser Tyr Phe Gly Va - #l Lys Val Ala Ile Ile          #10                 1 - #5                                                     - Glu Pro Gly Phe Phe Leu Thr Gly Val Thr Se - #r Ser Ala Arg Leu Cys          #             305                                                              - Ser Asn Thr Gln Met Leu Trp Asp Gln Thr Se - #r Ser Glu Ile Arg Glu          #        450                                                                   - Ile Tyr Gly Glu Lys Tyr Leu Ala Ser Tyr Le - #u Lys Arg Leu Asn Glu          #    60                                                                        - Leu Asp Lys Arg Cys Asn Lys Asp Leu Ser Le - #u Val Thr Asp Cys Met          # 80                                                                           - Glu His Ala Leu Thr Ala Cys                                                                  85                                                             - (2) INFORMATION FOR SEQ ID NO:26 :                                           -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 88 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY:  PCR c - #lone 200                                     #:    (xi) SEQUENCE DESCRIPTION: SEQ ID NO:26                                  - Ser Leu Arg Arg Asp Met Ala Pro Phe Gly Va - #l Gln Val Ser Ile Val          #                 15                                                           - Glu Pro Gly Phe Phe Arg Thr Pro Val Thr As - #n Leu Glu Ser Leu Glu          #            30                                                                - Ser Thr Leu Lys Ala Cys Trp Ala Arg Leu Pr - #o Pro Ala Ile Gln Ala          #        45                                                                    - His Tyr Gly Glu Ala Phe Leu Asp Thr His Le - #u Arg Val Gln Arg Arg          #    60                                                                        - Ile Met Asn Leu Ile Cys Asp Pro Glu Leu Th - #r Lys Val Thr Ser Cys          #80                                                                            - Leu Glu His Ala Leu Thr Ala Arg                                                              85                                                             - (2) INFORMATION FOR SEQ ID NO:27:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 88 amino                                                           (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY:  PCR c - #lone 215                                     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:27:                                 - Ser Leu Arg Arg Asp Val Ala Pro Phe Gly Va - #l Arg Val Ser Ile Val          #                 15                                                           - Glu Pro Gly Phe Phe Arg Thr Pro Val Thr As - #n Leu Glu Thr Leu Glu          #            30                                                                - Gly Thr Leu Gln Ala Cys Trp Ala Arg Leu Pr - #o Pro Ala Thr Gln Ala          #        45                                                                    - Leu Tyr Gly Glu Ala Phe Leu Thr Lys Tyr Le - #u Arg Val Gln Gln Arg          #    60                                                                        - Ile Met Asn Met Ile Cys Asp Pro Asp Leu Al - #a Lys Val Ser Arg Cys          #80                                                                            - Leu Glu His Ala Leu Thr Ala Arg                                                              85                                                             - (2) INFORMATION FOR SEQ ID NO:28:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 563 base                                                           (B) TYPE:nucleic acid                                                          (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: clone ME2 - #07.                                       -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:28:                                 - GAGGCGTTCT CGGACTCCCT CAGGAGGGGG CTCTCCTACT TTGGGGTGAA GG - #TGGCTATT          60                                                                           - ATAGAGCCTG GCTTCTTCCT GACCGGTGTG ACCAGTAGTG CCAGATTATG CT - #CAAATACC         120                                                                           - CAGATGCTGT GGGACCAGAC CAGCTCAGAA ATCAGGGAGA TCTATGGCGA GA - #AGTACCTG         180                                                                           - GCATCCTATC TGAAAAGGCT AAACGAATTG GACAAGAGGT GCAACAAGGA CC - #TGTCTTTG         240                                                                           - GTGACTGACT GCATGGAGCA TGCTCTGACT GCCTGCCACC CTCGCACGCG AT - #ACTCAGCT         300                                                                           - GGCTGGGATG CTAAGCTCTT CTACCTCCCC TTGAGCTACC TGCCTACCTT TC - #TTGTGGAT         360                                                                           - GCCCTTCTCT ATTGGACTTC CCTGAAGCCT GAGAAAGCCC TCTGACGTGT TC - #ACCTATGT         420                                                                           - GCATACCTGG GGAGATGTAG GTAGAGTTTG AGAGAGAGAA TATTTAGGGG AA - #ATTTGGAG         480                                                                           - GGTTGAGGGA GGGAGTTTAT TACTCTGGGG TTCAGTCAAC ACACTTCATC TC - #ATTAATTC         540                                                                           #               563AATA CTG                                                    - (2) INFORMATION FOR SEQ ID NO:29:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 134 amino                                                          (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (ix) FEATURE:                                                                      (A) NAME/KEY: clone ME2 - #07                                        -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:29:                                 - Glu Ala Phe Ser Asp Ser Leu Arg Arg Gly Le - #u Ser Tyr Phe Gly Val          #                 15                                                           - Lys Val Ala Ile Ile Glu Pro Gly Phe Phe Le - #u Thr Gly Val Thr Ser          #            30                                                                - Ser Ala Arg Leu Cys Ser Asn Thr Gln Met Le - #u Trp Asp Gln Thr Ser          #        45                                                                    - Ser Glu Ile Arg Glu Ile Tyr Gly Glu Lys Ty - #r Leu Ala Ser Tyr Leu          #    60                                                                        - Lys Arg Leu Asn Glu Leu Asp Lys Arg Cys As - #n Lys Asp Leu Ser Leu          #80                                                                            - Val Thr Asp Cys Met Glu His Ala Leu Thr Al - #a Cys His Pro Arg Thr          #                950                                                           - Arg Tyr Ser Ala Gly Trp Asp Ala Lys Leu Ph - #e Tyr Leu Pro Leu Ser          #           110                                                                - Tyr Leu Pro Thr Phe Leu Val Asp Ala Leu Le - #u Tyr Trp Thr Ser Leu          #       125                                                                    - Lys Pro Glu Lys Ala Leu                                                          130                                                                        - (2) INFORMATION FOR SEQ ID NO:30:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 18 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: forward p - #rimer                                     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:30:                                 #  18              TA                                                          - (2) INFORMATION FOR SEQ ID NO:31:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 20 base                                                            (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: nucleic acid                                         -     (ix) FEATURE:                                                                      (A) NAME/KEY: Reverse p - #rimer                                     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:31:                                 # 20               GGAA                                                        __________________________________________________________________________ 

We claim:
 1. An isolated cDNA molecule consisting of a nucleotide sequence which hybridizes, under stringent conditions, to the nucleotide sequence set forth in SEQ ID NO:
 10. 2. The isolated nucleic acid molecule of claim 1, wherein the nucleotide sequence of said isolated nucleic acid molecule comprises the nucleotide sequence set forth in SEQ ID NO:10.
 3. The isolated nucleic acid molecule of claim 1, wherein the nucleotide sequence of said isolated nucleic acid molecule comprises the nucleotide sequence set forth in SEQ ID NO:
 14. 4. An isolated genomic DNA molecule consisting of a nucleotide sequence which encodes the protein set forth in SEQ ID NO:15.
 5. An isolated nucleic acid molecule which encodes a boume protein having retinol dehydrogenase activity, whose amino acid sequence consists of the amino acid sequence of the protein encoded by the nucleotide sequence set forth in SEQ ID NO:
 10. 6. An isolated nucleic acid molecule which encodes a human protein having retinol dehydrogenase activity, whose amino acid sequence consists of the amino acid sequence set forth in SEQ ID NO:
 15. 7. An expression vector comprising the isolated nucleic acid molecule of claim 5, operably linked to a promoter.
 8. An expression vector comprising the isolated nucleic acid molecule of claim 6, operably linked to a promoter.
 9. A cell line or a bacterial cell strain, transformed or transfected with the expression vector of claim
 7. 10. A cell line or a bacterial cell strain, transformed or transfected with the expression vector of claim
 8. 11. An isolated nucleic acid molecule whose nucleotide sequence consists of a nucleotide sequence which encodes a human protein having retinol dehydrogenase activity, the complementary sequence of which hybridizes, under stringent conditions, to at least one nucleic acid molecule selected from the group consisting of SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, and SEQ ID NO: 23, and sequences complementary thereto.
 12. An isolated nucleic acid molecule which encodes a protein having retinol dehydrogenase activity, comprising a nucleotide sequence selected from the group consisting of SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 22, and SEQ ID NO:
 23. 